An integral
impeller and
fuel pump for a small gas
turbine engine, the
impeller being a centrifugal
impeller to supply
compressed air to the
combustor, the rotor disk of the
centrifugal compressor having at least one radial fuel passage connecting a central bore of the rotor disk to a fuel
nozzle located on the rear face of the rotor disk. A low pressure fuel supplied by a small pump delivers the fuel to the central bore where the fuel is collected within
helical grooves and channeled into the radial fuel passages where the fuel is pressurized to a relatively
high pressure due to the high rotational speed of the
centrifugal compressor. Highly compressed fuel is injected into the
combustor through fuel nozzles in an axial direction as the rotor disk rotates.
Helical grooves in the central bore each connected to a radial fuel passage move the fuel to an opposite side of the central bore to counteract rotor imbalance. In another embodiment, a primary annular groove collects fuel and, at a
low speed, passes all of the fuel to a first radial fuel passage into a first fuel
nozzle such that only some of the fuel nozzles inject fuel into the
combustor. At a higher speed, some of the fuel collected in the primary annular groove is spilled over into a secondary annular groove that passes the spilled-over fuel into a second radial passage and second fuel
nozzle such that all of the fuel nozzles inject fuel into the combustor.